This invention relates to a process for laboratory dyeing of, for example, carpet samples by the application of a defined amount of dyestuff onto the face of the carpet sample and transportation of this sample into a laboratory steamer wherein the sample is kept in motion.
In order to avoid rejects in the continuous dyeing manufacture of lengths of textile material, it is customary to test the respective dyeing effect at least on a laboratory scale. For this purpose, a sample piece of the length of material is conveyed over a dyestuff applicator and then introduced into the steamer for dye fixation. Only after the fixing step is the dye effect to be evaluated. For obtaining comparable production conditions even during laboratory dyeing, it is important to utilize the same application method and to record the exact amount of dyestuff applied. Also the steaming of the sample piece should, if at all possible, be carried out so that comparable production conditions are created. However, since a laboratory-scale continuous process dyeing plant is too expensive, one had to be satisfied, heretofore, with compromise solutions. Although the dyestuff was applied in accordance with the flow coating principle, the sample piece was disposed on an endless belt, with the drawback that the pile, for example when dyeing carpet material, was not opened up. Subsequently, the sample piece was transferred manually into the steamer. The best laboratory steamer was, heretofore, provided with a needle inlet, the sample piece being pinned to the needles thereof. On account of this fastening of the sample piece, the piece could then also be steamed in vertical extension ---- as customary in the production festoon steamers. Additionally, the sample piece could also be moved during the entire steaming period, namely repeatedly upwards and downwards.
It has been found time and again that this laboratory dyeing process is inadequate. Flawed continuous dyeing effects could not be avoided, solely due to the fact that also these laboratory dyeing conditions could not be reproduced in the continuous procedure.